LXR linux/fs/ocfs2/mmap.c

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/* -*- mode: c; c-basic-offset: 8; -*-
   3 * vim: noexpandtab sw=8 ts=8 sts=0:
   4 *
   5 * mmap.c
   6 *
   7 * Code to deal with the mess that is clustered mmap.
   8 *
   9 * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
  10 */
  11
  12#include <linux/fs.h>
  13#include <linux/types.h>
  14#include <linux/highmem.h>
  15#include <linux/pagemap.h>
  16#include <linux/uio.h>
  17#include <linux/signal.h>
  18#include <linux/rbtree.h>
  19
  20#include <cluster/masklog.h>
  21
  22#include "ocfs2.h"
  23
  24#include "aops.h"
  25#include "dlmglue.h"
  26#include "file.h"
  27#include "inode.h"
  28#include "mmap.h"
  29#include "super.h"
  30#include "ocfs2_trace.h"
  31
  32
  33static vm_fault_t ocfs2_fault(struct vm_fault *vmf)
  34{
  35        struct vm_area_struct *vma = vmf->vma;
  36        sigset_t oldset;
  37        vm_fault_t ret;
  38
  39        ocfs2_block_signals(&oldset);
  40        ret = filemap_fault(vmf);
  41        ocfs2_unblock_signals(&oldset);
  42
  43        trace_ocfs2_fault(OCFS2_I(vma->vm_file->f_mapping->host)->ip_blkno,
  44                          vma, vmf->page, vmf->pgoff);
  45        return ret;
  46}
  47
  48static vm_fault_t __ocfs2_page_mkwrite(struct file *file,
  49                        struct buffer_head *di_bh, struct page *page)
  50{
  51        int err;
  52        vm_fault_t ret = VM_FAULT_NOPAGE;
  53        struct inode *inode = file_inode(file);
  54        struct address_space *mapping = inode->i_mapping;
  55        loff_t pos = page_offset(page);
  56        unsigned int len = PAGE_SIZE;
  57        pgoff_t last_index;
  58        struct page *locked_page = NULL;
  59        void *fsdata;
  60        loff_t size = i_size_read(inode);
  61
  62        last_index = (size - 1) >> PAGE_SHIFT;
  63
  64        /*
  65         * There are cases that lead to the page no longer belonging to the
  66         * mapping.
  67         * 1) pagecache truncates locally due to memory pressure.
  68         * 2) pagecache truncates when another is taking EX lock against 
  69         * inode lock. see ocfs2_data_convert_worker.
  70         * 
  71         * The i_size check doesn't catch the case where nodes truncated and
  72         * then re-extended the file. We'll re-check the page mapping after
  73         * taking the page lock inside of ocfs2_write_begin_nolock().
  74         *
  75         * Let VM retry with these cases.
  76         */
  77        if ((page->mapping != inode->i_mapping) ||
  78            (!PageUptodate(page)) ||
  79            (page_offset(page) >= size))
  80                goto out;
  81
  82        /*
  83         * Call ocfs2_write_begin() and ocfs2_write_end() to take
  84         * advantage of the allocation code there. We pass a write
  85         * length of the whole page (chopped to i_size) to make sure
  86         * the whole thing is allocated.
  87         *
  88         * Since we know the page is up to date, we don't have to
  89         * worry about ocfs2_write_begin() skipping some buffer reads
  90         * because the "write" would invalidate their data.
  91         */
  92        if (page->index == last_index)
  93                len = ((size - 1) & ~PAGE_MASK) + 1;
  94
  95        err = ocfs2_write_begin_nolock(mapping, pos, len, OCFS2_WRITE_MMAP,
  96                                       &locked_page, &fsdata, di_bh, page);
  97        if (err) {
  98                if (err != -ENOSPC)
  99                        mlog_errno(err);
 100                ret = vmf_error(err);
 101                goto out;
 102        }
 103
 104        if (!locked_page) {
 105                ret = VM_FAULT_NOPAGE;
 106                goto out;
 107        }
 108        err = ocfs2_write_end_nolock(mapping, pos, len, len, fsdata);
 109        BUG_ON(err != len);
 110        ret = VM_FAULT_LOCKED;
 111out:
 112        return ret;
 113}
 114
 115static vm_fault_t ocfs2_page_mkwrite(struct vm_fault *vmf)
 116{
 117        struct page *page = vmf->page;
 118        struct inode *inode = file_inode(vmf->vma->vm_file);
 119        struct buffer_head *di_bh = NULL;
 120        sigset_t oldset;
 121        int err;
 122        vm_fault_t ret;
 123
 124        sb_start_pagefault(inode->i_sb);
 125        ocfs2_block_signals(&oldset);
 126
 127        /*
 128         * The cluster locks taken will block a truncate from another
 129         * node. Taking the data lock will also ensure that we don't
 130         * attempt page truncation as part of a downconvert.
 131         */
 132        err = ocfs2_inode_lock(inode, &di_bh, 1);
 133        if (err < 0) {
 134                mlog_errno(err);
 135                ret = vmf_error(err);
 136                goto out;
 137        }
 138
 139        /*
 140         * The alloc sem should be enough to serialize with
 141         * ocfs2_truncate_file() changing i_size as well as any thread
 142         * modifying the inode btree.
 143         */
 144        down_write(&OCFS2_I(inode)->ip_alloc_sem);
 145
 146        ret = __ocfs2_page_mkwrite(vmf->vma->vm_file, di_bh, page);
 147
 148        up_write(&OCFS2_I(inode)->ip_alloc_sem);
 149
 150        brelse(di_bh);
 151        ocfs2_inode_unlock(inode, 1);
 152
 153out:
 154        ocfs2_unblock_signals(&oldset);
 155        sb_end_pagefault(inode->i_sb);
 156        return ret;
 157}
 158
 159static const struct vm_operations_struct ocfs2_file_vm_ops = {
 160        .fault          = ocfs2_fault,
 161        .page_mkwrite   = ocfs2_page_mkwrite,
 162};
 163
 164int ocfs2_mmap(struct file *file, struct vm_area_struct *vma)
 165{
 166        int ret = 0, lock_level = 0;
 167
 168        ret = ocfs2_inode_lock_atime(file_inode(file),
 169                                    file->f_path.mnt, &lock_level, 1);
 170        if (ret < 0) {
 171                mlog_errno(ret);
 172                goto out;
 173        }
 174        ocfs2_inode_unlock(file_inode(file), lock_level);
 175out:
 176        vma->vm_ops = &ocfs2_file_vm_ops;
 177        return 0;
 178}
 179
 180